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- // Copyright 2017 Google LLC
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
-
- package pubsub
-
- import (
- "errors"
- "fmt"
- "sync/atomic"
- "testing"
- "time"
-
- "golang.org/x/net/context"
- "golang.org/x/sync/errgroup"
- )
-
- func TestFlowControllerCancel(t *testing.T) {
- // Test canceling a flow controller's context.
- t.Parallel()
- fc := newFlowController(3, 10)
- if err := fc.acquire(context.Background(), 5); err != nil {
- t.Fatal(err)
- }
- // Experiment: a context that times out should always return an error.
- ctx, cancel := context.WithTimeout(context.Background(), 5*time.Millisecond)
- defer cancel()
- if err := fc.acquire(ctx, 6); err != context.DeadlineExceeded {
- t.Fatalf("got %v, expected DeadlineExceeded", err)
- }
- // Control: a context that is not done should always return nil.
- go func() {
- time.Sleep(5 * time.Millisecond)
- fc.release(5)
- }()
- if err := fc.acquire(context.Background(), 6); err != nil {
- t.Errorf("got %v, expected nil", err)
- }
- }
-
- func TestFlowControllerLargeRequest(t *testing.T) {
- // Large requests succeed, consuming the entire allotment.
- t.Parallel()
- fc := newFlowController(3, 10)
- err := fc.acquire(context.Background(), 11)
- if err != nil {
- t.Fatal(err)
- }
- }
-
- func TestFlowControllerNoStarve(t *testing.T) {
- // A large request won't starve, because the flowController is
- // (best-effort) FIFO.
- t.Parallel()
- ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
- defer cancel()
- fc := newFlowController(10, 10)
- first := make(chan int)
- for i := 0; i < 20; i++ {
- go func() {
- for {
- if err := fc.acquire(ctx, 1); err != nil {
- if err != context.Canceled {
- t.Error(err)
- }
- return
- }
- select {
- case first <- 1:
- default:
- }
- fc.release(1)
- }
- }()
- }
- <-first // Wait until the flowController's state is non-zero.
- if err := fc.acquire(ctx, 11); err != nil {
- t.Errorf("got %v, want nil", err)
- }
- }
-
- func TestFlowControllerSaturation(t *testing.T) {
- t.Parallel()
- const (
- maxCount = 6
- maxSize = 10
- )
- for _, test := range []struct {
- acquireSize int
- wantCount, wantSize int64
- }{
- {
- // Many small acquires cause the flow controller to reach its max count.
- acquireSize: 1,
- wantCount: 6,
- wantSize: 6,
- },
- {
- // Five acquires of size 2 will cause the flow controller to reach its max size,
- // but not its max count.
- acquireSize: 2,
- wantCount: 5,
- wantSize: 10,
- },
- {
- // If the requests are the right size (relatively prime to maxSize),
- // the flow controller will not saturate on size. (In this case, not on count either.)
- acquireSize: 3,
- wantCount: 3,
- wantSize: 9,
- },
- } {
- fc := newFlowController(maxCount, maxSize)
- // Atomically track flow controller state.
- var curCount, curSize int64
- success := errors.New("")
- // Time out if wantSize or wantCount is never reached.
- ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
- defer cancel()
- g, ctx := errgroup.WithContext(ctx)
- for i := 0; i < 10; i++ {
- g.Go(func() error {
- var hitCount, hitSize bool
- // Run at least until we hit the expected values, and at least
- // for enough iterations to exceed them if the flow controller
- // is broken.
- for i := 0; i < 100 || !hitCount || !hitSize; i++ {
- select {
- case <-ctx.Done():
- return ctx.Err()
- default:
- }
- if err := fc.acquire(ctx, test.acquireSize); err != nil {
- return err
- }
- c := atomic.AddInt64(&curCount, 1)
- if c > test.wantCount {
- return fmt.Errorf("count %d exceeds want %d", c, test.wantCount)
- }
- if c == test.wantCount {
- hitCount = true
- }
- s := atomic.AddInt64(&curSize, int64(test.acquireSize))
- if s > test.wantSize {
- return fmt.Errorf("size %d exceeds want %d", s, test.wantSize)
- }
- if s == test.wantSize {
- hitSize = true
- }
- time.Sleep(5 * time.Millisecond) // Let other goroutines make progress.
- if atomic.AddInt64(&curCount, -1) < 0 {
- return errors.New("negative count")
- }
- if atomic.AddInt64(&curSize, -int64(test.acquireSize)) < 0 {
- return errors.New("negative size")
- }
- fc.release(test.acquireSize)
- }
- return success
- })
- }
- if err := g.Wait(); err != success {
- t.Errorf("%+v: %v", test, err)
- continue
- }
- }
- }
-
- func TestFlowControllerTryAcquire(t *testing.T) {
- fc := newFlowController(3, 10)
-
- // Successfully tryAcquire 4 bytes.
- if !fc.tryAcquire(4) {
- t.Error("got false, wanted true")
- }
-
- // Fail to tryAcquire 7 bytes.
- if fc.tryAcquire(7) {
- t.Error("got true, wanted false")
- }
-
- // Successfully tryAcquire 6 byte.
- if !fc.tryAcquire(6) {
- t.Error("got false, wanted true")
- }
- }
-
- func TestFlowControllerUnboundedCount(t *testing.T) {
- ctx := context.Background()
- fc := newFlowController(0, 10)
-
- // Successfully acquire 4 bytes.
- if err := fc.acquire(ctx, 4); err != nil {
- t.Errorf("got %v, wanted no error", err)
- }
-
- // Successfully tryAcquire 4 bytes.
- if !fc.tryAcquire(4) {
- t.Error("got false, wanted true")
- }
-
- // Fail to tryAcquire 3 bytes.
- if fc.tryAcquire(3) {
- t.Error("got true, wanted false")
- }
- }
-
- func TestFlowControllerUnboundedBytes(t *testing.T) {
- ctx := context.Background()
- fc := newFlowController(2, 0)
-
- // Successfully acquire 4GB.
- if err := fc.acquire(ctx, 4e9); err != nil {
- t.Errorf("got %v, wanted no error", err)
- }
-
- // Successfully tryAcquire 4GB bytes.
- if !fc.tryAcquire(4e9) {
- t.Error("got false, wanted true")
- }
-
- // Fail to tryAcquire a third message.
- if fc.tryAcquire(3) {
- t.Error("got true, wanted false")
- }
- }
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